A technical question that I guess isn't really important for anyone here but just wondering...

From what I'm reading of info found on the internet; injector placement closer to the valve is good for emissions and idle quality, and further away promotes better atomization. So port injection production cars have them close to the valve, and F1 has them outside of the itb pointing in the direction of flow...

My question is regarding the injector further away from the valve:

With any efi engine at top rpm the injector is close to being always open. So having the injector spraying into a mostly stale tract would just be pooling the fuel until the valve opens and sucks it all in, thus negating most advantages of this atomization and furthering wall wetting???

In that case wouldn't having the injector at the valve eg like our Kjet heads be the best placement? The added benefit would be atomizing the fuel on the hot valve...

And side question, would the only reason Volvo went to the injector boss in manifold setup have been cost related? Because not only is the injector further away from the valve but now there is this obtrusion in the manifold.

At WOT you have a lot of reversion in the manifold runner. Any footage of induction systems shows the fuel mist flowing back up the runner and wetting the wall, often projecting back into the main chamber. F1 may have placed the injector further away to maximise the benefits of reversion and minimise the volumetric loss due to the atomised/vapourised fuel.

As for the injector location, I'd say cost was one consideration due to producing k-jet and LH at the same time. Others may have been better mixing in the air stream or even the impacts of EGR. I certainly don't know why they made some of their choices.

Ok. So I thought atomised and vaporised fuel was an aid to volumetric efficiency? I'm not educated in this so my wording may be incorrect here. My knowledge extends as far as this off the bat reading... Saying vapour leads me to believe it's as good as it can get with air/fuel dispersion.

Relating this to our Volvo's and red blocks in particular. Would there be any real world point in deciding where to put the injector? Forgetting costs of tooling and manufacturing, say one was to have a sheet metal fabricated intake with good flow etc, would there be any benefits in having the injector placed where they typically are in the intake runner?

My question is coming from seeing injectors in intake manifolds only being able to inject at an angle not perpendicular to air flow, sometimes directly onto the wall of the intake, where as the kjet placement is literally pointed at the valve. Seems preferable to me.

It seems easier to me to drill injector bosses than weld in bungs and worry about angles etc...

Take a look at inlet manifolds the Scandinavian builders have,some can be purchased , big TB and injectors to suit big turbo applications usually , maybe not suitable for N/A but there are N/A ones to look at. I know K L Racing do stuff.

I would love a CNC mill and lathe to make stuff like that! (And the know how.....)

Nowadays 3D printing can be used too!

I guess so. And when I think about it as far as I know no one has placed injectors in the head at the valve since kjet. So there must be more benefit to placing them that little extra back for any purpose than I am realising.

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